This invention relates to explosives and more particularly to nitroaromatic explosives.
2,4,6-trinitrotoluene (TNT) shrinks when it cools, frequently causing TNT castings to crack. The addition of 1 percent by weight of 2,2',4,4',6,6'-hexanitrostilbene (HNS) to the TNT reduces or eliminates this shrinkage. HNS is also an excellent explosive. As a result, there is an increasing market for HNS.
Two methods of preparing 2,2',4,4',6,6'hexanitrostilbene (HNS) are disclosed in U.S. Pat. No. 3,505,413, entitled "Hexanitrostilbene," issued to Kathryn, G. Shipp on Apr. 7, 1970. In the first 2,4,6-trinitrotoluene was reacted with 5 percent sodium hypochlorite (Clorox) at 0.degree. C. in a tetrahydrofuran (THF)-methanol solvent mixture to produce HNS in a single step (disclosed yield 42%). In the second method, the above conditions were used except that the reaction was stopped after one minute by drowning the reaction mixture in very dilute hydrochloric acid. The reported yield of 2,4,6-trinitrobenzyl chloride was 85 percent. Next the 2,4,6-trinitrobenzyl chloride was reacted at room temperature with sodium hydroxide to give HNS (reported yield 50%). Thus, the yield of HNS using the two step method was 0.85.times.0.50 =0.425 or 42.5%. It would be desirable to find a method of substantially increasing this yield.